In the past, silver-made jewelry, artistically crafted items, and the like represented by, for example a ring or the like, have been manufactured by, in general, casting or forging a silver-containing material. However, in recent years, silver clay (clayish composition for forming a sintered body) including silver powder has become commercially available, and a method is suggested that manufactures silver jewelry or artistically crafted items having an arbitrary shape by making the silver clay into an arbitrary shape and then firing the silver clay (for example, refer to Patent Document 1). According to such a method, silver clay can be freely shaped like general clay is shaped, therefore silver-made jewelry, artistically crafted items and the like can be manufactured in an extremely simple manner by drying a shaped body obtained by shaping and then firing the shaped body using a furnace.
Meanwhile, the silver clay described in Patent Document 1 is, in general, obtained by adding a binder or water, and, as a necessity, a surface active agent or the like to the powder of pure silver (pure Ag) and then kneading the mixture. However, in a case in which silver clay is made using silver powder of pure Ag and then heated so as to manufacture a silver sintered body, there is a problem in that the obtained silver sintered body has poor strength characteristics since the strength of pure Ag itself is weak.
To solve the above-described problem of the strength characteristics, another method is also suggested that manufactures a silver sintered body, which is a so-called sterling silver, by shaping and then firing silver clay obtained by constituting a silver powder with a silver alloy including Ag in a component ratio of 92.5% and, furthermore, copper (Cu) or the like, and adding the silver powder to a binder or the like and kneading the mixture (for example, refer to the ‘Example’ section or the like in Patent Document 2).